Chromatographic methods of analysis fairly common in determination of chemical composition of metal and ceramic precursors and successfully used in analysis of a variety of objects (water, air, polymers) are not widely used in the aviation industry. Herein, we consider a possibility of using chromatographic methods in aviation industry, in particular, in analysis of polymeric materials with a goal of optimization of technological processes and quality control of the manufactures. Application of chromatographic methods to analysis of workplace air provides assessing the quality of conformance to sanitary and ecological standards.

Results of a comparative study of the composition of 3,3’-dichloro-4,4’- diaminodiphenylmethane samples of different trade marks (Diamet-X (Russia, MOSA (China), Kuralon and Kuamin (Japan)) using chromato-mass spectrometry are presented. Purity of the product is shown to increase in a series of MOCA - Kuamin - Kuralon - Diamet X. We identified the main impurities (including diazotizable) in Diamet X and foreign-made analogues and proposed patterns of their fragmentation under electron impact. Data obtained are used for developing a procedure of analysis of 3,3’-dichloro -4,4’-diaminodiphenylmethane samples for the total content of diazotizable substances and residual o-chloroaniline.

A new voltammetric method is developed for quantitative determination of coenzyme Q₁₀ in aqueous media using dc cathodic voltammetry on a glassy carbon electrode in Biologically Active Dietary Supplements. A well-defined reduction peak of coenzyme was obtained at -0.6 V vs. Ag/AgCl. The impact of pH on the redox properties of coenzyme Q₁₀ is considred. The linearity of the calibration curve within the concentration range from 10 to 100 mg/m, provides determination of coenzyme Q₁₀ in BADSs. Metrological characteristics of the developed voltammetric method are calculated. A spectrophotometric determination of coenzyme Q₁₀ in the real samples is used for comparison.

A method of Al₂O₃, SiO₂, CaO, Fe₂O₃ determination in silica refractories using ICP-AES with microwave sample preparation in an autoclave is developed. Composition of an acidic mixture and mode of microwave step-heating are elaborated to provide completeness of sample dissolution and exclude losing of the analytes in the form of volatile compounds due to autoclave depressurization. We proposed to use Cd as an internal standard. Calibration curves for determination of standard macro- and microelements in terms of oxides using ICP-AES are obtained by the method of three standards. The validity of the developed method is confirmed in analysis of certified reference materials and comparison with the results of AL₂O₃, SiO₂, CaO, Fe₂O₃ determination according to standard (GOST) procedures. The developed method provides 11-fold shortening of the overall duration of the analysis, and 8-fold decrease in consumption of concentrated acids.

Advantages of manufacturing precision optical coatings by magnetron sputtering with a power supply of a gas discharge in mid-frequency range of currents (applied to magnetron sputtering system (MSS)) are described. The importance of choosing optimal characteristics and operating modes of MSS power supply sources is demonstrated. The samples of TiO₂ films have been fabricated using the developed technological equipment of magnetron sputtering including multimode power supply system ofMSS at different frequencies of voltage pulses applied to MSS (other sputtering conditions being the same). The samples are studied using laser ellipsometry, atomic force microscopy, x-ray diffraction and x-ray reflectometry. The impact of pulsed current frequency fmag on the functional properties of TiO₂ films such as refractive index, density, and roughness is shown.

Comparative analysis of the characteristics of electrolytes obtained using chemical analysis and x-ray diffraction technique by the method of standards and Rietveld method is carried out. The reliability of the method of standards is confirmed in the course of quantitative analysis of electrolytes from several factories using domestic diffractometers “DIFRAY-402.” Data of quantitative phase analysis (method of standards and Rietveld method) of lithium-free electrolyte samples with a cryolite ratio CR < 2,5 correlate well with the results of chemical analysis. For potassium and lithium-containing electrolytes with CR > 2,5 the determined phase composition differs from the real one because the thorium method usually overestimates CR, whereas the standard way of cryolite ratio calculation leaves out sodium containing in potassium and lithium phases.

We present a simulation method providing estimation of vibratory acceleration spectra of the elements of operating stator of the turbogenerator having defects weakening the attachment fittings. A methodology and results of experimental determination of the frequency characteristics of the accelerance of the turbogenerator stator structure from the places of defect origination to hull plating of the stator are presented. The developed procedure is intended for testing turbogenerators of power plants in the state of overhaul and/or bench testing at the manufacture plants. We used a method of impact excitation by the exciter unattached to the structure. A list of measurement equipment and error of determination of the frequency characteristic of the calibration block is presented. Comparative analysis of the frequency characteristics obtained on four stators of TVV-320-2 turbogenerators which differ in technical conditions and service life (which included estimation of the correctness of measurements) demonstrated the possibility of assessing the frequency characteristics of the stator proceeding from the data obtained for the only one turbogenerator of each type. The scheme of placing sensors on the stator hull provides detection of the defects within a sector with the central angle 90^o. The obtained estimates of the frequency characteristics of the stator structure can be used for simulation modeling of vibroacoustic fluctuations of the stator hull plating for working turbogenerator having defects of weakening the attachment fittings with the goal of assessing the possibility of detecting defects through spectral symptoms attributed to stator derangement. Shortcomings of the instant impact model are considered. Examples and recom mendations regarding construction of dynamic models of the stator defects are given.

A technique of experimental determination of axial and tangential (circumferential) residual stresses in the surface layer of the vee (bottom) of a large thread is considered with allowance for plane stress state. Diagrams of the residual stress distribution in the depth of the surface layer of the vee of the outer thread 164 x 6 are plotted with allowance for planar (biaxial) stress state. Lateral and circular samples with dimension of a cross section, providing a linear stress state are cut from thread- containing parts. A surface layer of the thread is removed by electrochemical etching in a special unit and residual strain of the sample is measured. The dependences that can be used in calculation of axial and tangential residual stresses as functions of sample deformation upon cutting and removing of the surface layer are obtained.

Experimental data on uniaxial testing of polyurethane material duothan QA965, as well as the results of testing polyurethane damper exposed to positive and negative temperatures are presented. A significant increase in the modulus of elasticity is observed in the temperature range from -30 to -35°C. The exact solution of the problem of axisymmetric strain of the cylindrical damper is compared to the results of physical modeling of its behavior at room temperature. Results of numerical calculation (Mooney - Rivlin model) match well the experimental data.

Sources of the errors of photometric and voltammetric determination of Mn and Fe in welding aerosols collected on a filter are studied using standardized techniques. Study of synthetic samples corresponding in composition to the real samples demonstrated the significance of the systematic error for Mn determination, whereas for Fe the discrepancy between real and found values exhibited a random character. Model dependences of the error of Mn determination on the chemical composition of the samples are obtained. It is shown that the errors of photometric and voltammetric determination of Mn upon thermal ashing of the material depend on the type of compound and content of SiO₂; correctness of voltammetric determination of Mn also depends on the content of Fein the samples. Systematic errors of Mn determination using photometric and voltammetric analysis can attain 15 and 50 % rel., respectively.

We substantiate the structure of metrological assurance of the conformity assessment in the quality control of coatings proceeding from the system ensuring the uniformity of measurements of the indicators used to characterize the quality of coatings and consider the spectrum of related problems.